Radioelectric finding and telemetering system



Dec 6, 1949 HARDY 2,49%,951

RADIOELECTRIC FINDING AND TELEMETERING SYSTEM Filed May 28, 1943 2 Sheets-Sheet 1 I I H IY ii W A z INVEN TOR.

FEM; hi4 RDY BY Ah 1 AM Dec. 6, 1949 HARDY 2,490,651

RADIOELECTRIC FINDING AND TELEMETERING SYSTEM Filed- May 28, 1943 2 Sheets-Sheet 2 F f Fig.5 TRANSMITTER- P0455 SNDR COLLECTOR A/vrs/v/was r RCE./V/?

I SUPPLY CIRCUIT D/J TR/BUTOR f7 SUPPLY CIRCUIT- INVENTOR.

I RENE fM/QDY ATTURNEY rannies Dec. c, 1949 UNITED RADIOELECTRIC FINDING AND TELE- METERING SYSTEM I Ren Hardy, Lyon, France, assigno: to International Standard Electric Corporation, New

York, N. Y.

Application May 2a, 1943, Serial No. 488,814

France December 20, 1940 Section 1, Public Law 690, August a, 1946 Patent expires December 20, 1960 a s 0. (Cl. 343-11) The present invention relates to radioelectric findingand telemetering-systems.

According to one Of its aspects, the invention is intended particularly to provide radioelectric finding-systems for determining with precision the direction of a Hertzian-wave transmittin source or of an obstacle, such as an airplane, from which a brief signal is reflected back.

Such radioelectric direction-finding systems also permit of obtaining by Hertzian waves the distance of a detected object in addition to determining its direction. However, in order to use radio direction-finders for this double determination of direction and distance, it is necessary to provide two or more radio direction-finders arranged at a base and to centralize the information conveyed by them so as to determine by triangulation the distance and the direction of a detected object, Hertzian source, or obstacle with respect to the centralizing station.

According to another of its aspects, therefore,

the present invention is intended to provide directionand distance-metering systems or radio- According to certain features of the invention,

a radio direction-finding system of the type in which the direction e. g of an echo source is given by a maximum or minimum reception over a directional antenna-system, comprising two antennas separated by a Hertzian screen, the assembly being orientable and connected to an amplifying-system differentially feeding an inertialess indicator, such as a cathode-ray tube, the amplifying-system being arranged to amplify al ternately the energy coming from the two antennas.

According to other features of the invention, a radio goniotelemetric system comprises a slowly rotating transmitter-receiver assembly arranged to control simultaneously two indicating-devices, one indicating direction and the other indicating distance, in order to reveal at all times the presence of an obstacle in space and indicate the direction and the distance or that obstacle without hiiigrr-upting the continuous Watch of the space w These objects and features, as well as still others, will be set fonthin detail-in the descrip tion that follows, givenwith reference to the accompanying drawings, in which:

Fig. 1 shows schematic-ally an embodiment, incorporating features of the invention, of a radio direction-finder having a differential indicator;

Fig. 2 shows curves used in explaining the operation of the system shown in Fig. 1;

Fig. 3 shows schematically another embodiment, according to certain features of the invention, or a radio direction-finder which also provides for measuring distances;

Fig. 4 shows a portion ofth cathodic screen of the direction-indicator shown in Fig. 3; and

Fig. 5 shows schematically a possibiearrangegn ieng of the double indicating-device shown in One plan, in general, is to provide two directional antennas, one .on each side of a static screen and connected oneeachto two'tuned grid circuits of two difiere'nt tubes, Alternating voltage from a transformer is connected to the screen grids or the same tubes by a-sort' of push-pull arrangement in such amanner that the tubes will be effective alternately The object of this is to se arate two antenna circuits so that the radio frequency will be brought'but ingroups of cycles This antenna system can-be oriented at will.

Each antenna Al and A2 therefore has a diflerent reception-pattern but the orientation of the assembly provides equal reception in a quite definite direction with respect to the Hertzian-wave. or echo source whose distance it is desired to determine.

Antennas Al and A2, whose wave-structure amplifier. Tubes VI and V2 are shown as being screen-grid tubes and the gain of VI and of V2 is variable, being controlled b the sinusoidal voltage of a generator (not shown) applied to these screen-grids across transformer B. The sinusoidal voltage applied by S serves to cause tubes VI and-V2 to operate alternately.

At A in Fig. 2 is shown the gain variation of tubes VI and V2. When VI amplifies, V2 does not operate, and vice versa. The dotted curve marked Iv: is the gain curve corresponding to VI, and the solid-line curve marked Ky: is that corresponding to V2. It will be seen that each tube amplifies alternately during one-half period of the sinusoidal voltage applied by S.

The plate-circuits of tubes VI and V2 supply in common another amplifier-stage comprising only one tube (V3) across a tuned-secondary transformer HI. Tube V2 also is shown in the form of a screen-grid tube, although it may be an emplifier tube ofany suitable type.

At B in Fig. 2 is shown the high-frequency current passing through amplifier V3, assuming that the reception over antenna AI be stronger than When there is a difi'erence in the reception over antennas AI and A2, hence in the output currents of tubes V5 and V6, line T will be displaced towards the right or towards the left; thus, by orienting wave-collector assembly AI, P, A2 in the direction of the wave sought, an indication T will be obtained that will be displaced on the screen and pass by line N the moment the airplane or other moving body towards which a brief-signal wave is directed and which reflects It back finds itself on the axis of collector AI, A2, P.

It should be understood, naturally, that the control of the input-and output-tubes VI, V2 and V5, V6 of the amplifier system can be obtained in a different way than through the use of a sinusoidal voltage on the screen-grids or these tubes in order to 'assure their alternate operation.

' These tubes may be of some other than the over antenna A2. The result is that during all the half-periods that VI has a high gain, current HFv: will be substantial, while it will be of less value during the other half-periods, when V2 will have a high gain, because A2 receives less energy thanAI.

The current amplified by V3 is impressed across the primary of a tuned-secondary transformer H2 to a diode detector tube V4. This current will have a profile similar to the envelope of current Eliva. At C in Fig. 2 curve Vu represents the voltage appearing in the tuned circuit M of diode Vl. This variable voltage appearing in M is applied in parallel to the control grids of two amplifier tubes V5 and Vi constituting the output stage. The screen grids of these two tubes are modulated at the same time as those of the two input tubes VI and V2 by the same sinusoidal voltage as indicated by the transformer bearing the same reference character 5. It is obvious, however, that all the usual phase and other precautions may be taken to ensure perfect balance of the circuits.

Sinusoidal voltage 8 distributes to V5 and VI amounts of current proportional to those enterin: VI and V2, and, when wave-collector AI, P, A2 is so oriented that there is equal reception over AI and A2, the average output currents of V5 and V6 will be equal. The time-constant filters shown at R, C are inserted in the output circuits of tubes V5 and V6 in order to give the mean currents a' continuous shape. These currents thus flattened are applied respectively to plates P11, P1 of a cathode-ray indicator I in such a way that, when the output currents of V5 and V are equal, the spot will remain on line N. In order better to read the visual indication, the spot is given an alternate vertical deflection, by means of a sinusoidal voltage applied through transformer X--X to plates Pr, Pa" of the oscillograph. The indication thus obtained is a line T when there is equal reception over antennas AI and A2.

screen-grid type and may be controlled by deflection of the electronic beam, by cutting of! the control grid, etc.

It is likewise obvious that the curves of Fig. 2 are given only by way of illustration and that the variations shown in that figure may be of other shapes.

Such a direction-determining device may be combined with a second similar one so as to find out the two space-planes on which the obstacle is' located, while the distance will be taken on a third cathode-tube through examination of the pulses on a time base.

However, such a directionand distance-metering arrangement comprising a transmitter and two receivers will not be convenient in all cases, owing to the space taken up by the devices. That. is why, according to certain of its features, the invention provides more simple and less bulky arrangements for performing such radioelectric goniotelemetric operations. An example of such an arrangement is shown schematicall in Fig. 3.

In that figure, an assembly N of transmittercollector antennas of any suitable structure whose instantaneous orientation is indicated at F is driven continuously by a motor M at relatively low speed, for example one revolution about every three seconds. Motor M simultaneously controls a. distributor A which applies circular-scanning sinusoids over wires SI and S2 in quadrature to the pairs of deflecting-plates Pa, Pr and P11, P11, respectively, of a cathode-ray indicator I, so that the lines ON, OE, OS and OW on the screen of tube I will correspond respectively to the north. east, south, and west directions in space. The cathodic spot thus describes a circle V on the screen of cathode ray tube I.

At each turn of the antennas and of the spot, which follows in synchronism, there is produced a short pulse emitted by N and generated by a pulse-sender G but which may be of any suitable known type and which controls at once the emission of pulses by antenna system N and the return to zero of the linear time-base of a second cathode ray oscillograph I used for measuring distances.

The pulse emitted at each turn is sent out exactly at one turn plus a fraction of a turn; that is, if the emission pulse appeared on the screen of cathode-ray tube I, it would be seen through successive appearances at TI, T2, T3,, etc., the spot making the complete turn of circle V in 3 seconds. I

However, the pulse cannot appear unless it is reflected back by an obstacle and amplified by pulse-receiver R, i. e., when it encounters an obstacle such as an airplane, for example. Receiver It mayalso consist of any other suitable cise angle of the bearing of the detected obstacle.-

Fig. 4 shows such an indication at T, the bearing angle being the angle a. made by the axis of the maximum pulse with line N.

In order to cause this return .pulse to appear on the screen of cathode ray indicator 1, receiver R operates through radial modulation the supply Bi of cathode tube indicator I. The radial-modulation control of cathode tube 1 is shown in known form as being efiected througha grid modulation of the cath ode ray tube, supply circuit Bl supplying the various electrodes Of the electron gun of cathode ray tube I through potentiometer p.

Receiver R at the same time controls another supply circuit (B2) for a second cathode ray tube (1'), on which the distance indications are read, this second tube being controlled by a linear modulation so as to allow in an easy manner, through antennas while permitting overlapping of said. 3 field patterns, a'pair of vacuum tubes,- means to connect one of said antennas to the grid of one of said tubes, means to connect the other of said antennas to the grid of the other of said tubes, means to operate said tubes alternately, an indicating device comprising a cathode ray tube, and means responsive to the difference in the outputs of said vacuum tubes to control the movement of the spot of the cathode ray tube in one direction.

2. A radio direction finding system comprising a pair of directional antennas mounted in fixed relation to each other and rotatable in the plane of the field patterns of said antennas so as to permit them to scan a predetermined field in space, means to separate the major portions of the field patterns of said antennas while permitting overlapping of said patterns, a first pair of tubes, means to connect one of said an- 7 tennas to the grid of one of said tubes, means the appearance of return pulses T on its screen,

the reading of the distance D on the distancescale. Such a linear-scanning circuit is well known and requires no further detailed descrip-. tion.

It should be understood that the radial modu lation whereby the pulses can be caused to appear on the screen of tube I is described only by way of example and that an other method of modulation may be used to furnish the desired indications of the return pulses. Likewise, the linearscanning modulation Of tube I is merely illustrative.

For indicator tube I it is also possible to provide, if. desired, a. modification of the circular scanning, that is, a modification of the voltage shapes causing that scanning, in order to give the resultant image the desired shape. Likewise, on the grid of tube I may be provided a control voltage assuring the illumination of the spot, in such a way that circle V shall be extinguished and only the pulses appear on the screen.

Such a system thus makes possible continuous scanning of space with an indication of the distance of the obstacle as soon as it appears, and of the direction in which it lies. The evolutions of an obstacle may thus be watched and followed with respect to the radioelectric goniotelemetric station.

For reading-convenience, the two indicating devices may be' mounted on one and the same chassis, as shown in Fig. 5, the assembly being attached to one of the ships panels, for example, if the station is arranged to be mounted on board a moving body.

While the invention has been described in the case Of certain specific embodiment examples, it is obvious that it is in no way limited thereto but that on the contrary it is capable of many modifications and adaptations without departing from its scope.

I claim:

1. A radio direction finding system'comprising a pair of directional antennas in fixed relation to each other but orientably mounted so as to scan a predetermined field in space, means to separate to connect the other of said antennas to the grid of the other of said tubes, operating control means to operate said tubes alternately, means to combine the outputs of said tubes in a common output circuit, means to detect the signal insaid common output circuit, a second pair of tubes, means to apply the detected signal to the grids of both said second pair of tubes in parallel,

tube, means to smooth the output of said tube so as to deliver a substantially constant voltage to said deflecting plate, means to deliver the output of the other of said second pair of tubes to the other deflecting plate, and means to smooth the output of said other tube so as to deliver a substantially constant voltage to said other deflecting plate.

3. A radio direction finding system in accordance with claim 2 in which the cathode ray tube is provided with a second pair of deflection plates and means for applying alternating voltage of a predetermined frequency between the second pair of plates.

4. A radio direction finding system in accordance with claim 1 further comprising means to control the movement of the spot of the cathode ray tube at a predetermined rapid rate in the other direction while the aforesaid means controls the movement in said one direction.

5. A radio direction finding system, comprising means to radiate pulses of electromagnetic waves, a directional antenna system rotatable in a given plane, receiving means responsive to the output energy of said antenna system, a first indicating device, means to control operation of said first device in one. coordinate of a two coordinate system in accordance with the rotation of said antenna system, means to operate said first device in the other.coordinate by the response of said received energy to indicate the direction of received energy, a second indicating device, means the major portions or the field patterns of said 15 in; means to radiate pulses of electromagnetic a given plane, receiving means responsive to the output energy of said antenna system, a first cathode say tube, means to control said tube in one coordinate of a two coordinate system in accordance with the rotation of said antenna system, means to operate said tube in the other coordinate by the response of said received energy, a second cathode ray tube. means to control operation of said second tube in one coordinate oi. a two coordinate system responsive to the radiation of a pulse of electromagnetic waves, and means to operate the second tube in' the other coordinate by the response of said received energy.

RENE HARDY.

8 nu'nalmcas crrm flle of this patent:

16 Number UNITED STATES m'rm'rs Name Date Willoughby June 5, 1934 Wright Jan. 10, 1939 Hershberxer Feb. 8, 1940 Steinhofl Apr. 16, 1940 Deerhake Feb. 18, 1947 Miller June 17, 1947 FOREIGN PATENTS Country Date Great Britain Jan. 21, 1942 

